Power supply changeover arrangement



2,118,976; rownn stmrrwcnmsenovnm I :Al lamHolstrom, Rochesten. Y.,.assignor, by mesne assignments to General. Dynamics Corporation, a corpontoon of Delaware Application Angu'sw 1954,.SerlaliNoa448fi9fl sclaims. 12131546 i S tes, Patent combination: adaptedto operate from aconvenient source er. on E2 2. power sneh as that obtained by plugging 'apower cord into awall receptacle; The second-source of ower: generally comprises set of self-contained batteries; My'invention is particularly'directed: to means I for efleoti-nga; changeover from one or thesepow'er: supp1-iesito the other, and. is especially' concerned with the mentioned is; the conservation of battew' powerwhen the receiver is operatedi'onz'battetiesu Wlrembattery operation isv under way, the user of the receiver, frequently wiill a'cceptla lowering of output volume if battery power can be conserved; This procedure is acceptable because most occasions on which battery power is being used are those where it is relatively quiet, and a large audio output power is not necessary. Unfortunately, battery changeover circuits known before my invention have not been adapted to the conservation of battery power.

It is accordingly an object of my invention to provide a new and improved power supply changeover arrangement for a radio receiver.

It is another object of my invention to provide a power supply changeover arrangement for a radio receiver which accommodates a means for conserving battery power when batteries are in use.

It is also an object of my invention to provide a radio receiver power supply changeover arrangement which will accommodate a means for conserving battery power, yet which is inoperative to reduce output audio power when the receiver is operated from an A.-C. or D.-C. external source.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawing which shows in block diagram fashion, the major elements of a typical A.-C., D.-C., battery portable radio, together with the. detailed circuits involved in a preferred embodiment of my invention.

Referring now to the drawing, there are shown the elements of a typical A.-C., D.-C., battery portable receiver comprising a converter stage 1, an I.-F. amplifier 2, a detector and first audio stage 3, and an output stage 4. An antenna 5 may be connected to the input of converter 1 and a loudspeaker or other suitable transducer 6 may be connected to the output of audio output stage 4. Each of stages 1 to 4 typically employs a single tube, as

"ice

indicated by'a circle-within each ofthe respeetive blocl i's, which ingeneraf has a filamentary heater. Thus-con verter 1 employs a singletube indicated by symbol 7 and having a fiiamentfig ImF. amplifier 2 has a single tube indicated" generally at n and? having a filament 10; stage 3 employsa-single-tubeindicated generally at-II and having a filament- 12;" and audio output'stage 4 employs a* singletube indica-ted' generally at. 13-, but inthis case having a'.-fil"arr'1ent withmultiple sections'14and 15; These sections are connected series, and have acenterrtap 1 6 tlierebetween.

As' isusual inradioreeeiver's of the Aa-Ql', Di-(Qi, battery type, there is provided a first source of power such as that lying. within cfashed reetangle 1 7. This source may include capacitor 18}. halfwaverectifier 19", resistor 20, capacitor 21 and resistor 22. Filament power maybe obtained 'from*lead2'3'; and anode power from lead 24. Power for thefirst. source" of'supply 17- may be=obtaihed by plugging line cord connector 27-'i-nto an appropriate receptacle; There is also provided a second source of filament power eonsi 'sting'of Ai battery 25. The battery source for anode operation may be B battery 26.

In accordance withmy'inventionl provide an'arrangment including a changeover switch 28 for'changing-over from power Suppl 1 7 to thesecon'd', or battery, supply 25 26; This: switch may'eomprisea number of gangs' one oflth'ese gangs", indicatedbyreferenee symbol 29; is indicated block diagram form" only because it may be ofany well hnown configuration andin any event formal n part of my invention.

- Further in accordance with my prefer that allcornponents e-=ope rat'edtween-es whenever changeoverswitch-N is rn' th'e lett'-hand;.orK- .-Cl, position. I rt the leffiitaindgpositi'on, a filament supply circuit is established from power source III, ositive read 2e,

contact 30 of switch 28, switch arm 31, switch arm 32, contact 33, resistor 34, filament section 15 of tube 13, filament section 14 of tube 13, filament 12,'filament 10, filament 8, to ground at point 35. The other side of the circuit i completed from ground 36, on-oif switch 37, switch arm 38, contact 39, to negative power supply lead 40.

By placing changeover switch 28 in the second, or righthand, position, an optimum circuit for operation from battery 25 is obtained. The electron discharge devices or tubes of the receiver are divided into first and second groups. The first group includes tubes 7 and 9 with their filaments 8 and 10 connected in series. The second groupincludes tubes 11 and 13, with filament 12 and filamentsection 14 of tube 13 connected in series.

In accordance with my invention, I prefer that the series-connected filaments of the first group of tubes, namely filaments 8 and 10, be connected in parallel with the series-connected filaments of the second group of tubes up to and including the second filament section 14 of the tube in the second group having a multi-section filament. For battery operation, changeover switch 28 is also effective to connect the series combination of filament section 15 and resistor 34 in parallel with the foregoing parallel connection.

Changeover switch 28 is further operative to disconnect the filaments from the first source of power 17 and to connect the second source of filament power, battery 25, across the parallel connection pointed out above. One path of this parallel connection may be traced from positive terminal 41 of battery 25, switch arm 42, contact 43, filament 10, and filament 8 to ground 35. A second path leads from contact 43 to filaments 12 and filament section 14, contact 44 and switch arm 45 to ground at 46.

The third arm of the foregoing parallel connection extends from positive terminal 41 of battery 25, contact 47, switch arm 31, switch arm 32, contact 33, resistor 34, filament switch 48, thereby disconnecting filament section 15 from battery 25. Tube 13 continues to operate because filament section 14 is unaffected. I It should be noted that switch 48 is effective to disconnect filament section 15 only when changeover switch 28 is in the righthand, or battery operation, position. When switch means 28 is in the left-hand, or A.-C., D.-C. operation, position, on the other hand, the effect of switch means 48 is cancelled, since'power supply 17 cannot be disconnected from filament section 15 by switch means 48. In this way, my invention achieves its object of providing a power supply changeover arrangement in which battery power may be conserved by the user when batteries are in use, but audio output power cannot inadvertently be sacrificed during A.-C., D.-C. operation.

While I have shown and described my invention as applied to a specific embodiment thereof, other modifications will readily occur to those skilled in the art.

I do not, therefore, desire my invention to be limited to the specific arrangement shown and described, and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim is:

1. In a radio receiver, a first group of electron discharge devices having filaments connected in series; a second group of electron discharge devices having filaments connected in series, one electron discharge device in said second group having first andsecond filament sections connected in series, and a center tap therebetween; first and second sources of filament power; first switch means having a first position operative to connect said filaments of'said electron discharge devices in said first and second groups in series to said first source of filament power, and having a second position operative to connect the series-connected filaments of said first group of electron discharge devices in parallel with the series-connected filaments of said second group of electron discharge devices up to and including said first filament section of said one electron discharge device, operative also to connect said second filament section of said one electron discharge device in parallel with the foregoing said parallel connection, and further operative to disconnect said first source of power from said filaments and to connect said second source of power across said parallel connections; second switch means operative to disconnect said second filament section of said one electron discharge device from said second source of power; and means for cancelling the effect of said second switch means when said first switch means is in said first position.

2. The combination of claim 1 in which resistance means are connected in series with said second section of said filament of said one electron discharge device, said resistive means having a value of resistance such that a voltage drop across said second section and said resistance means in series is equal to the drop across the series connection of said filaments in said first group of electron discharge devices.

3. In radio apparatus, a plurality of operatively coupled electron discharge devices, said devices each having a filamentary cathode; a first, a second, and a third cathode circuit; two power sources, a plurality of switches with a common actuator, a first group of said switches for connecting said first, second and third cathode circuits in series and across one of said sources, a second group of said switches for connecting said first and second cathode circuits in parallel and across said second source and for open circuiting said third cathode circuit.

References Cited in the file of this patent UNITED STATES PATENTS 

